In a distributed business systems landscape, any two or more business systems communicating with each other must agree on and use a common communications interface. A business system cannot unilaterally alter the agreed upon interface contract without breaking the ability to communicate with the other system or systems. A unilateral alteration can occur in the example of a first business system in a landscape being upgraded to a new software or operating system version that has enhanced interfaces while one or more other systems with which the first system communicates are not upgraded. In this example situation or in others in which one but not all communicating system undergo an interface change, communications between systems with incompatible interfaces can fail. For example, a newer version may communicate using data objects containing additional data field that are not present in and therefore not recognized by an older version of the interface.
One approach to this problem can be the use of process oriented field extensibility in which customer extension fields are forwarded across systems, for example of an external service provider, that have been specifically prepared for communication with a system that operates on a different interface version. This approach can be quite cumbersome, as it requires action for any communicating system as soon as any other system within a networked architecture undergoes an interface change.
As more and more business systems in a networked landscape communicate with each other, the interdependencies increase to a point where either the whole landscape needs to be upgraded at the same time or not at all. Neither alternative is desirable.